p?ungqr
p?ungqr
Generates the complex unitary matrix
Q
of the QR
factorization formed by p?geqrf
.Syntax
void
pcungqr
(
MKL_INT
*m
,
MKL_INT
*n
,
MKL_INT
*k
,
MKL_Complex8
*a
,
MKL_INT
*ia
,
MKL_INT
*ja
,
MKL_INT
*desca
,
MKL_Complex8
*tau
,
MKL_Complex8
*work
,
MKL_INT
*lwork
,
MKL_INT
*info
);
void
pzungqr
(
MKL_INT
*m
,
MKL_INT
*n
,
MKL_INT
*k
,
MKL_Complex16
*a
,
MKL_INT
*ia
,
MKL_INT
*ja
,
MKL_INT
*desca
,
MKL_Complex16
*tau
,
MKL_Complex16
*work
,
MKL_INT
*lwork
,
MKL_INT
*info
);
Include Files
- mkl_scalapack.h
Description
This
function
generates the whole or part of m
-by-n
complex distributed matrix Q
denoting A
(ia
:ia
+m
-1, ja
:ja
+n
-1) with orthonormal columns, which is defined as the first n
columns of a product of k
elementary reflectors of order m
Q
= H
(1)*H
(2)*...*H
(k
)as returned by
p?geqrf
. Input Parameters
- m
- (global) The number of rows in the matrix sub(Q);(.m≥0)
- n
- (global) The number of columns in the matrix sub(Q) (m≥n≥0).
- k
- (global) The number of elementary reflectors whose product defines the matrixQ(n≥k≥0).
- a
- (local)Pointer into the local memory to an array of size. Thelld_a*LOCc(ja+n-1)j-th columnof the matrix stored inmust contain the vector that defines the elementary reflectoraH(j),ja≤j≤ja+k-1, as returned byp?geqrfin thekcolumns of its distributed matrix argumentA(ia:*,ja:ja+k-1).
- ia,ja
- (global) The row and column indices in the global matrixAindicating the first row and the first column of the submatrixA, respectively.
- desca
- (global and local) array of sizedlen_. The array descriptor for the distributed matrixA.
- tau
- (local)Array of size.LOCc(ja+k-1)Contains the scalar factortau[of elementary reflectorsj]H(as returned byj+1)p?geqrf(0 ≤.j<)LOCc(ja+k-1)tauis tied to the distributed matrixA.
- work
- (local)Workspace array of size oflwork.
- lwork
- (local or global) size ofwork, must be at leastlwork≥nb_a*(nqa0 +mpa0 +nb_a), whereiroffa=mod(ia-1,mb_a),icoffa=mod(ja-1,nb_a),iarow=indxg2p(ia,mb_a,MYROW,rsrc_a,NPROW),iacol=indxg2p(ja,nb_a,MYCOL,csrc_a,NPCOL),mpa0 =numroc(m+iroffa,mb_a,MYROW,iarow,NPROW),nqa0 =numroc(n+icoffa,nb_a,MYCOL,iacol,NPCOL)indxg2pandnumrocare ScaLAPACK tool functions;MYROW,MYCOL,NPROWandNPCOLcan be determined by calling thefunctionblacs_gridinfo.If, thenlwork= -1lworkis global input and a workspace query is assumed; thefunctiononly calculates the minimum and optimal size for all work arrays. Each of these values is returned in the first entry of the corresponding work array, and no error message is issued by pxerbla.
Output Parameters
- a
- Contains the local pieces of them-by-ndistributed matrixQ.
- work[0]
- On exitcontains the minimum value ofwork[0]lworkrequired for optimum performance.
- info
- (global)= 0: the execution is successful.< 0: if thei-th argument is an array and thej-th entry, indexedhad an illegal value, thenj- 1,info= -(i*100+j); if thei-th argument is a scalar and had an illegal value, theninfo=-i.